The present invention is directed to an oligomeric dispersant. More particularly, the present invention is directed to an oligomeric dispersant for cementitious particles. Specifically, the present invention is directed to a reaction product of a moiety that adsorbs onto a particle to be dispersed, a moiety that provides the dispersing capability, and an optional moiety that is disposed between the other moieties to provide connections between the other moieties.
A cementitious mixture refers to pastes, mortars, and concrete compositions comprising a hydraulic cement binder. Pastes are defmed as mixtures composed of a hydraulic cement binder, either alone or in combination with pozzolans such as fly ash, silica fume, or blast furnace slag, and water. Mortars are defined as pastes that additionally include fine aggregate. Concretes additionally include coarse aggregate. These compositions may additionally include other admixtures such as set retarders, set accelerators, defoaming agents, air-entraining or air detraining agents, corrosion inhibitors, water reducing agents, pigments, and any other admixture that does not adversely affect the advantageous results obtained by the present invention.
Dispersants are substances that improve the flow characteristics of the cement slurry by breaking up cement agglomerates and freeing the water, thus giving slurries of lower viscosity and allowing desirable flow conditions to be obtained at lower pump pressures. V.S. Ramachandran, Concrete Admixtures Handbook: Properties, Science, and Technology, Noyes Publications (Second Edition, 1995).
Dispersants have been used in the construction industry to disperse cementitious mixtures. Dispersants such as sulfonated melamine formaldehyde condensate (SMF), sulfonated naphthalene formaldehyde condensate (BNS), and lignosulfonates are commonly used as dispersants. However, these compounds require more than the desired amount of material to achieve a desired level of concrete workability or water reduction. In addition, these materials do not achieve full range (Type A to Type F) water reducing capability, as defined in ASTM C494. For example, lignosulfonates achieve only a low to mid range (5-12%) water reduction before severe set retardation occurs.
Dispersants are a necessary component in high strength and high durability concretes. Due to the requirement for the use of low water amounts in high performance concretes, sometimes high dispersant amounts are necessary to achieve workable concretes. High BNS levels can lead to undesirable retardation of set and may not provide the required workability retention over time.
It is desirable to provide a material that is several times more efficient as a cement or concrete dispersant than the traditional materials like lignosulfonates, BNS and SMF. Improving efficiency reduces the amount of material required to achieve a desired level of concrete workability or water reduction. With respect to the presently used dispersants, lignosulfonates, BNS and SMF, it is also desirable to improve slump retention while maintaining normal setting characteristics. Providing a dispersant with full range (Type A to F) water reducing capability is also a desirable characteristic.
One improvement in the prior art was to use polycarboxylate dispersants. Polycarboxylate dispersants are structured with a polymeric backbone, such as a carbon chain backbone, with pendant moieties. The pendant moieties provide the dispersing capabilities of the dispersant. Polycarboxylate dispersants are polymers with a carbon backbone with pendant side chains, wherein at least a portion of the side chains are attached to the backbone through a carboxyl group or an ether group. For example, polyacrylic acid has carboxylic groups attached to the backbone. Also, side chain moieties such as polyoxyalkylenes can be attached to the carboxylic groups to provide further dispersing capabilities. These dispersants operate by surrounding a particle to be dispersed, and then repulsion forces between each polymer chain keeps the particles apart and more fluid.
It is therefore an object of the invention to provide oligomeric dispersants for dispersing cementitious particles, wherein the dispersant adsorbs onto the particle to be dispersed.
The present invention provides a cementitious formulation comprising a cement and a dispersant comprising a reaction product of component A, component B, and component C; wherein each component A is independently a nonpolymeric, functional moiety that adsorbs onto a cementitious particle, and contains at least one residue derived from a first component selected from the group consisting of phosphates, phosphonates, phosphinates, hypophosphites, sulfates, sulfonates, sulfmates, alkyl trialkoxy silanes, alkyl triacyloxy silanes, alkyl triaryloxy silanes, borates, boronates, boroxines, phosphoramides, amines, amides, quaternary ammonium groups, carboxylic acids, carboxylic acid esters, alcohols, carbohydrates, phosphate esters of sugars, borate esters of sugars, sulfate esters of sugars, salts of any of the preceding moieties, and mixtures thereof; wherein component B is independently a nonpolymeric moiety that is disposed between the component A moiety and the component C moiety, and is derived from at least one of an alicyclic hydrocarbon and a heterocyclic hydrocarbon; and wherein component C is at least one moiety that is a linear or branched water soluble, nonionic polymer substantially non-adsorbing to cement particles, and is selected from the group consisting of poly(oxyalkylene glycol), poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), monoalkoxy poly(oxyalkylene glycol), monoaryloxy poly(oxyalkylene glycol), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof; wherein if the A moiety contains any phosphate, phosphonate, phosphinate, or hypophosphite residue the dispersant is further characterized by at least one of the following:
A) the dispersant has a structure selected from the group consisting of:
(C)zxe2x80x94Bxe2x80x94Axxe2x80x94Bxe2x80x94(C)z,xe2x80x83xe2x80x83(i)
(Ax)yxe2x80x94Bxe2x80x94Cxe2x80x94Bxe2x80x94(Ax)y,xe2x80x83xe2x80x83(ii)
xe2x80x83and mixtures thereof;
B) the dispersant has a structure of (Ax)yxe2x80x94Bxe2x80x94(C)z with the proviso that the B moiety and the A moiety are not bound to each other through an alkylidene amine linkage;
C) the C moiety is selected from the group consisting of poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof;
wherein x is an integer from 1 to 3 and represents the number of independent A moieties, y is an integer from 1 to 3 and represents the number of independent A moieties, and z is an integer from 1 to 3 and represents the number of independent C moieties.
The present invention also provides a cementitious formulation comprising a cement and a dispersant comprising a reaction product of component A, optionally component B, and component C; wherein each component A is independently a nonpolymeric, functional moiety that adsorbs onto a cementitious particle, and contains at least one residue derived from a first component selected from the group consisting of phosphates, phosphonates, phosphinates, hypophosphites, salts of any of the preceding moieties, and mixtures thereof; wherein component B is an optional moiety, where if present, each component B is independently a nonpolymeric moiety that is disposed between the component A moiety and the component C moiety, and is derived from a second component selected from the group consisting of linear saturated hydrocarbons, linear unsaturated hydrocarbons, saturated branched hydrocarbons, unsaturated branched hydrocarbons, alicyclic hydrocarbons, heterocyclic hydrocarbons, aryl, phosphoester, nitrogen containing compounds, and mixtures thereof; and wherein component C is at least one moiety that is a linear or branched water soluble, nonionic polymer substantially non-adsorbing to cement particles, and is selected from the group consisting of poly(oxyalkylene glycol), poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), monoalkoxy poly(oxyalkylene glycol), monoaryloxy poly(oxyalkylene glycol), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof; wherein if the A moiety contains any phosphate, phosphonate, phosphinate, or hypophosphite residue the dispersant is further characterized by at least one of the following:
A) the dispersant has a structure selected from the group consisting of:
Axxe2x80x94C,xe2x80x83xe2x80x83(i)
Axxe2x80x94Cxe2x80x94Ax,xe2x80x83xe2x80x83(ii)
Cxe2x80x94Axxe2x80x94C,xe2x80x83xe2x80x83(iii)
(C)zxe2x80x94Bxe2x80x94Axxe2x80x94Bxe2x80x94(C)z,xe2x80x83xe2x80x83(iv)
(Ax)yxe2x80x94Bxe2x80x94Cxe2x80x94Bxe2x80x94(Ax)y,xe2x80x83xe2x80x83(v)
xe2x80x83and mixtures thereof;
B) the dispersant has a structure of (Ax)yxe2x80x94Bxe2x80x94(C)z with the proviso that the B moiety and the A moiety are not bound to each other through an alkylidene amine linkage;
C) the C moiety is selected from the group consisting of poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof;
wherein x is an integer from 1 to 3 and represents the number of independent A moieties, y is an integer from 1 to 3 and represents the number of independent A moieties, and z is an integer from 1 to 3 and represents the number of independent C moieties.
The present invention also provides a method of dispersing a cementitious formulation comprising cement in water, comprising providing in said cementitious formulation one of the above referenced dispersants and mixing said cementitious formulation.
The present invention also provides a cementitious formulation comprising a cement and a blocked oligomeric dispersant comprising a reaction product of component A, component B, and component C; wherein each component A is independently a blocked, nonpolymeric, functional moiety that adsorbs onto a cementitious particle after deblocking, and contains at least one residue derived from a first component selected from the group consisting of alkyl trialkoxy silanes, alkyl triacyloxy silanes, alkyl triaryloxy silanes, and mixtures thereof; wherein component B is independently a nonpolymeric moiety that is disposed between the component A moiety and the component C moiety, and is derived from at least one of an alicyclic hydrocarbon and a heterocyclic hydrocarbon; wherein component C is at least one moiety that is a linear or branched water soluble, nonionic polymer substantially non-adsorbing to cement particles, and is selected from the group consisting of poly(oxyalkylene glycol), poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), monoalkoxy poly(oxyalkylene glycol), monoaryloxy poly(oxyalkylene glycol), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof; and wherein the blocked oligomeric dispersant is present in the cementitious formulation in combination with a second dispersant selected from the group consisting of an oligomeric dispersant, a cementitious dispersant, and mixtures thereof; wherein the oligomeric dispersant comprises a reaction product of component A1, optionally component B1, and component C1; wherein each component A1 is independently a nonpolymeric, functional moiety that adsorbs onto a cementitious particle, and contains at least one residue derived from a first component selected from the group consisting of phosphates, phosphonates, phosphinates, hypophosphites, sulfates, sulfonates, sulfmates, alkyl trialkoxy silanes, alkyl triacyloxy silanes, alkyl triaryloxy silanes, borates, boronates, boroxines, phosphoramides, amines, amides, quaternary anmmonium groups, carboxylic acids, carboxylic acid esters, alcohols, carbohydrates, phosphate esters of sugars, borate esters of sugars, sulfate esters of sugars, salts of any of the preceding moieties, and mixtures thereof; wherein component B1 is an optional moiety, where if present, each component B1 is independently a nonpolymeric moiety that is disposed between the component A1 moiety and the component C1 moiety, and is derived from a second component selected from the group consisting of linear saturated hydrocarbons, linear unsaturated hydrocarbons, saturated branched hydrocarbons, unsaturated branched hydrocarbons, alicyclic hydrocarbons, heterocyclic hydrocarbons, aryl, phosphoester, nitrogen containing compounds, and mixtures thereof; and wherein component C1 is at least one moiety that is a linear or branched water soluble, nonionic polymer substantially non-adsorbing to cement particles, and is selected from the group consisting of poly(oxyalkylene glycol), poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), monoalkoxy poly(oxyalkylene glycol), monoaryloxy poly(oxyalkylene glycol) poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof.
The present invention also provides a method of dispersing a cementitious formulation comprising cement in water, comprising providing in said cementitious formulation the above referenced blocked oligomeric dispersant and mixing said cementitious formulation.
The oligomeric cement dispersant of the present invention does not have a polymeric backbone with pendant groups like dispersants of the prior art. Rather, the oligomeric cement dispersant has a moiety that will adsorb onto the particle to be dispersed by means of one or more residues attached to an adsorbing moiety of absolute molecular weight. The adsorbing moiety acts as an xe2x80x9canchorxe2x80x9d to hold the dispersant onto the particle to be dispersed.
One embodiment of the present invention is a composition of matter adapted for dispersing cementitious particles in water comprising a reaction product of component A, optionally component B, and component C.
Each component A is independently a nonpolymeric, functional moiety that adsorbs onto a particle, and contains at least one residue derived from a component selected from the group consisting of phosphates, phosphonates, phosphinates, hypophosphites, sulfates, sulfonates, sulfinates, alkyl trialkoxy silanes, alkyl triacyloxy silanes, alkyl triaryloxy silanes, borates, boronates, boroxines, phosphoramides, amines, amides, quaternary ammonium groups, carboxylic acids, carboxylic acid esters, alcohols, carbohydrates, derivatives of carbohydrates, salts of any of the preceding moieties, and mixtures thereof. Derivatives of carbohydrates include, but are not limited to, phosphate esters of sugars, borate esters of sugars, and sulfate esters of sugars.
The salt of moiety A is selected from the group consisting of lithium, sodium, potassium, calcium, magnesium, aluminum, iron, arrmonia, amines, and mixtures thereof. The term amines is meant to include primary, secondary, and tertiary amines, including, but not limited to, substituted amines such as triethanolamine or morpholine.
Molecules satisfying the requirement of the A moiety include, but are not limited to, multihydroxy compounds, such as sugars, sugar acids, lactones of sugar acids, sugar alcohols, tris(hydroxymethyl) aminomethane, phosphate esters of sugars, borate esters of sugars, sulfate esters of sugars, alkyl phosphates, substituted alkyl phosphates, alkyl phosphonates, substituted alkyl phosphonates, alkyl phosphinates, substituted alkyl phosphinates, aryl boronic acids, esters of aryl boronic acids, aryl dioxaborolanes, triaryl boroxines, trialkoxyboroxines, alkyl trialkoxy silanes, alkyl triacyloxy silanes, alkyl triaryloxy silanes, hydroxy carboxylic acids, non-polymeric polycarboxylic acids, and mixtures thereof. The alkyl groups in the above molecules are generally C1 to about C6 groups, the aryl groups in the above molecules are generally about C6 to about C10 groups, and the acyl groups in the above molecules are generally C1 to about C6 groups. The substituted alkyls can be hydroxyalkyls or carboxyalkyls.
Illustrative examples of molecules used to construct the A moiety include, but are not limited to, 2-carboxyethyl phosphonic acid, sulfosuccinic acid, citric acid, ascorbic acid, 2-phosphono-1,2,4-butane tricarboxylic acid, glucuronic acid, ethylenediaminetetraacetic acid, gluconic acid, cyclohexane hexacarboxylic acid, mellitic acid, saccharic acid, mucic acid, diethylenetriamine pentaacetic acid, glucoheptonic acid, glucoheptonic lactone, lactobionic acid, 3,3xe2x80x2,4,4xe2x80x2-benzophenone tetracarboxylic acid, 2-(4xe2x80x2carboxyphenyl)-1,3,2-dioxaborolane, triphenyl boroxine, 4-carboxyphenyl boronic acid, 4-formylphenyl boronic acid, 2-(4xe2x80x2-formylphenyl)-1,3,2-dioxaborolane, amino propyl trimethoxysilane, aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxy silane, 3-glycidoxypropyltriethoxysilane, 3-(triethoxysilyl)propyl isocyanate, 3-(trimethoxysilyl)propyl isocyanate, glucooctanoic-xcex3-lactone, glucose, leucrose, diaminopropane-N,N,Nxe2x80x2,Nxe2x80x2-tetraacetic acid, aconitic acid, isocitric acid, 1,2,3,4-butanetetracarboxylic acid, nitrilotriacetic acid, tricarballylic acid, N-(phosphonomethyl)iminodiacetic acid, 3-[[tris(hydroxymethyl)methyl]amino]-1-propanesulfonic acid, 2-[[tris(hydroxymethyl)methyl]amino]-1-ethanesulfonic acid, 3-[bis(2-hydroxyethyl)amino]-2-hydroxy-1-propanesulfonic acid, 3-[N-trishydroxymethylmethylamino]-2-hydroxypropanesulfonic acid, N-tris[hydroxymethyl]methyl-4-aminobutanesulfonic acid, 3-aminoadipic acid, aspartic acid, xcex1-glutamic acid, xcex2-glutamic acid, 1,3-diamino-2-hydroxypropane-N,N,Nxe2x80x2,Nxe2x80x2-tetraacetic acid, triethylenetetraaminehexaacetic acid, glucosamine, galactosamine, mannosamine, tris(hydroxymethyl)aminomethane, xcex3-carboxyglutamic acid, glucamine, glucosaminic acid, xcex2-carboxyaspartic acid, xcex1-hydroxymethylaspartic acid, tricine, 1,2,3,4-cyclopentanetetracarboxylic acid, 6-phosphogluconic acid, sorbitol, mannose, mannitol, mannonic acid, mannuronic acid, galactose, galactitol, galactaric acid, galacturonic acid, fructose, sucrose, salts of any of the preceding moieties, and mixtures thereof.
Each A moiety has one or more functional groups. When the A moiety has one functional group, two or more A moieties are combined to provide for multiple functional groups in the oligomeric dispersant. When the A moiety has multiple functionalities, there is no requirement that more than one A moiety must be used. examples of the residue include, but are not limited to, hydroxyl, carboxylate, sulfate, sulfonate, sulfinate, phosphate, phosphonate, phosphinates, borate, boronate, boroxine, dioxaborolane, amine, quaternary ammonium, and mixtures thereof. The functional groups attach to the cement particle to be dispersed by adsorbing onto the cement particle. The more functional groups that are present on the A moiety, the more strongly the A moiety can anchor to the cement particle.
Component B is an optional moiety, and if present, each B is independently a nonpolymeric moiety that is disposed between the A moiety and the C moiety, and is derived from a second component selected from the group consisting of C1 to about C6 linear saturated hydrocarbons, C1 to about C6 linear unsaturated hydrocarbons, C1 to about C6 branched saturated hydrocarbons, C1 to about C6 branched unsaturated hydrocarbons, about C5 to about C10 alicyclic hydrocarbons, about C4 to about C10 heterocyclic hydrocarbons, about C6 to about C10 arylenes, nitrogen containing compounds, and mixtures thereof. Nitrogen containing compounds include, but are not limited to, any amine, urea, or isocyanate. For heterocyclic hydrocarbons, the heteroatom is preferably nitrogen, oxygen, or sulfur. The heterocyclic hydrocarbons may contain more than one heteroatom. The heteroatoms in these multiple heteroatom heterocyclic hydrocarbons may all be the same heteroatom, or they can be different.
Illustrative examples of the B moiety include, but are not limited to, methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, isobutylene, neopentylene, propenylene, isobutenylene, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, a residue derived from toluene diisocyanate, a residue derived from isophorone diisocyanate, a residue derived from heterocyclic hydrocarbons containing two or three nitrogen heteroatoms, phenylene, substituted arylenes such as 
and mixtures thereof. Preferred nitrogen heteroatom heterocyclic hydrocarbons include residues derived from pyrazine, residues derived from pyridazine, residues derived from pyrimidine, residues derived from pyrazole, and residues derived from melamine.
Each C component is at least one moiety that is a linear or branched water soluble, nonionic polymer substantially non-adsorbing to cement particles, and is preferably selected from the group consisting of poly(oxyalkylene glycol), poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), monoalkoxy poly(oxyalkylene glycol), monoaryloxy poly(oxyalkylene glycol), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof.
The C moiety has a number average molecular weight from about 500 to about 100,000. Preferably, the C moiety has a number average molecular weight from about 1,000 to about 50,000. Most preferably, the C moiety has a number average molecular weight from about 1,000 to about 30,000.
The oligomeric dispersant of the present invention has number average molecular weight from about 650 to about 100,000. Preferably, the dispersant has a number average molecular weight from 1,150 to about 50,000. Most preferably, the dispersant has a number average molecular weight from about 1,150 to about 30,000.
The dispersant according to the present invention can have a structure represented by the following general formulas:
Axxe2x80x94C;xe2x80x83xe2x80x83(i)
Axxe2x80x94Cxe2x80x94Ax;xe2x80x83xe2x80x83(ii)
Cxe2x80x94Axxe2x80x94C;xe2x80x83xe2x80x83(iii)
(Ax)yxe2x80x94Bxe2x80x94(C)z;xe2x80x83xe2x80x83(iv)
(C)zxe2x80x94Bxe2x80x94Axxe2x80x94Bxe2x80x94(C)z;xe2x80x83xe2x80x83(v)
(Ax)yxe2x80x94Bxe2x80x94Cxe2x80x94Bxe2x80x94(Ax)y;xe2x80x83xe2x80x83(vi)
and mixtures thereof, wherein x is preferably an integer from 1 to 3 and represents the number of independent A moieties, y is preferably an integer from 1 to 3 and represents the number of independent A moieties, and z is preferably an integer from 1 to 3 and represents the number of independent C moieties.
For further clarification, Ax is preferably at least one of Axe2x80x94, Axe2x80x94Axe2x80x94, or Axe2x80x94Axe2x80x94Axe2x80x94;
Bxe2x80x94(C)z is preferably at least one of 
xe2x80x83and
(Ax)yxe2x80x94B is preferably at least one of 
If the A moiety contains any phosphate, phosphonate, phosphinate, or hypophosphite residue the dispersant is further characterized by at least one of the following:
A) the dispersant has a structure selected from the group consisting of:
Axxe2x80x94C,xe2x80x83xe2x80x83(i)
Axxe2x80x94Cxe2x80x94Ax,xe2x80x83xe2x80x83(ii)
Cxe2x80x94Axxe2x80x94C,xe2x80x83xe2x80x83(iii)
(C)zxe2x80x94Bxe2x80x94Axxe2x80x94Bxe2x80x94(C)z,xe2x80x83xe2x80x83(iv)
(Ax)yxe2x80x94Bxe2x80x94Cxe2x80x94Bxe2x80x94(Ax)y,xe2x80x83xe2x80x83(v)
xe2x80x83and mixtures thereof;
B) the dispersant has a structure of (Ax)yxe2x80x94Bxe2x80x94(C)z with the proviso that the B moiety and the A moiety are not bound to each other through an alkylidene amine linkage;
C) the C moiety is selected from the group consisting of poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof;
wherein x is an integer from 1 to 3 and represents the number of independent A moieties, y is an integer from 1 to 3 and represents the number of independent A moieties, and z is an integer from 1 to 3 and represents the number of independent C moieties.
In another embodiment, the above composition of matter is incorporated into a cementitious formulation with a hydraulic cement. The oligomeric dispersant can be added as an admixture alone or in combination with other admixtures in the field, or can be added to the cementitious formulation prior to delivery to the field.
The hydraulic cement comprising the cementitious formulation for which the dispersants are effective is selected from the group consisting of portland cement, masonry cement, oil well cement, alumina cement, refractory cement, magnesia cement, calcium sulfoaluminate cement, and mixtures thereof.
Aggregate can be included in the cementitious formulation to provide for mortars which include fine aggregate, and concretes which also include coarse aggregate. The fine aggregate are materials that pass through a Number 4 sieve (ASTM C125 and ASTM C33), such as silica sand. The coarse aggregate are materials that are retained on a Number 4 sieve (ASTM C125 and ASTM C33), such as silica, quartz, crushed round marble, glass spheres, granite, limestone, calcite, feldspar, alluvial sands, or any other durable aggregate, and mixtures thereof.
Additionally, cement admixtures may be included in the cementitious formulation. Cement additives that can be added include, but are not limited to, set accelerators, set retarders, air entraining agents, air detraining agents, foaming agents, defoaming agents, corrosion inhibitors, shrinkage reducing agents, other known dispersing agents, pozzolans, pigments, and mixtures thereof.
The cementitious formulation may further comprise water. The water can be present in an amount from about 20% to about 100% based on the dry weight of the cement.
The dispersant of the present invention is generally present in the cementitious formulation in an amount from about 0.005 to about 2% based on the dry weight of the cement. Preferably, the dispersant is present in an amount from about 0.01% to about 1%.
An additive selected from the group consisting of soil, calcined clay, and mixtures thereof can be included in the cementitious formulation. The soil can be any soil including, but not limited to, fme sands, silty soils, and clay. The additive can replace up to about 25% of the cement. Preferably, the additive replaces up to 20% of the cement.
In another embodiment of the present invention, there is provided a method of dispersing a cementitious formulation comprising a hydraulic cement in water, including providing in said cementitious formulation the above described oligomeric cement dispersant.
In another embodiment of the invention, an oligomeric dispersant wherein at least one A moiety in the oligomeric dispersant is blocked is used in combination with a second dispersant which is selected from another oligomeric dispersant of the present invention or any other suitable cementitious dispersant. By xe2x80x9cblockedxe2x80x9d it is meant that the residue on the A moiety does not interact with the cement until the residue is liberated. The residue is liberated/deblocked over time by hydrolyzing in the alkaline environment of the cementitious system. This provides for latent dispersant properties.
The effect of liberating over time results in a delay of dispersing performance that leads to extended slump retention performance. The residues on the A moiety that are blocked include, but are not limited to, trialkoxy silanes, triacyloxy silanes, and triaryloxy silanes. A preferred blocked residue is trialkoxy silanes.
The blocked oligomeric dispersant can be present in a cementitious formulation in an amount from about 0.005 to about 2% based on the dry weight of the cement. Preferably, the blocked oligomeric dispersant is present in an amount from about 0.01% to about 1%. Preferably, the ratio of the blocked oligomeric dispersant to the other dispersant is from about 1:10 to about 5:1. More preferably, the ratio is about 1:5 to about 3:1.
By any cementitious dispersant it is meant to include all chemicals that function as a dispersant, water reducing agent, or plasticizer for cement. Illustrative examples include, but are not limited to, sulfonated naphthalene formaldehyde polymers, sulfonated melamine formaldehyde polymers, lignosulfonates, polyacrylic acids, polymethacrylic acids, polycarboxylates, and polyaspartates.